Variable displacement oil pump

ABSTRACT

To provide a rotor portion 2A; a cam ring 21 having a rotor chamber 21a; a pump housing 1 provided with a pump chamber 11 having a control chamber 12 where the cam ring 21 is movably arranged to move the cam ring 21 using an oil pressure; a spool valve A for controlling the cam ring 21; a solenoid valve 81; and a relief valve 83. Each valve housing is provided with a communication hole 7 for supplying oil from the control chamber 12 of the pump chamber 11 to a portion between the control chamber 12 and at least one of the valve housings. A through-hole for discharging the oil is formed in the valve housing.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a variable displacement oil pump provided with a variable displacement mechanism such as a vane pump, capable of suppressing hunting caused by pulsation of a vane pump during a discharge operation with a very simple structure.

2. Description of the Related Art

Conventionally, various types of vane pumps capable of changing a discharge amount are known in the art. A representative example is discussed in Japanese Patent Application Publication No. 2015-21400. Japanese Patent Application Publication No. 2015-21400 discloses a variable displacement type pump capable of changing a pump discharge capacity by swinging a cam ring. However, it is known that the vane pump suffers from significant pulsation. In addition, the pulsation becomes significant as the discharge amount increases from zero by starting the pump.

SUMMARY OF THE INVENTION

In a variable displacement oil pump such as a vane pump, an inscribed gear pump, and a circumscribed gear pump, a pressure spike occurs in pulsation because an oil discharge operation is discontinuous. In a system in which a control chamber pressure is filled with a discharge pressure, such a pressure spike affects a behavior of a spool valve that operates the cam ring or the like using a hydraulic pressure and a pressure of the control chamber as a control target, so that a behavior of the variable operation of the cam ring becomes unstable, and a phenomenon in which the discharge pressure (amount) has a large amplitude occurs.

This phenomenon is called “hunting” and may affect a discharge function of the oil pump and make it difficult to obtain a satisfactory engine function. In this regard, an object of the present invention is to provide a variable displacement oil pump having a variable displacement mechanism such as a vane pump, capable of suppressing hunting generated from pulsation of the vane pump during a discharge operation with a very simple structure.

As a result of diligent studies to solve the aforementioned problems, the inventors solved the problems by providing, according to a first embodiment of the invention, a variable displacement oil pump including: a rotor portion; a cam ring having a rotor chamber for housing the rotor portion; a pump housing provided with a pump chamber having a control chamber where the cam ring is movably arranged to move the cam ring using an oil pressure; a spool valve; a solenoid valve; and a relief valve, wherein at least one of the spool valve, the solenoid valve, and the relief valve has a valve housing provided with a communication hole for supplying oil from the control chamber between the control chamber of the pump chamber and at least one of the valve housings, and a through-hole for discharging oil is formed in the valve housing provided with the communication hole. A second embodiment of the present invention solves the problems by providing the variable displacement oil pump of the first embodiment, in which the rotor portion includes a vane rotor and a plurality of vanes. A third embodiment of the present invention solves the problems by providing the variable displacement oil pump of the first embodiment, in which the rotor portion has an inner rotor having outer teeth and an outer rotor that has inner teeth that form cells along with the outer teeth and rotates with a predetermined eccentricity with respect to a rotation center of the inner rotor, a protrusion is formed in an outer circumference of the cam ring, and the protrusion is placed in the control chamber.

Fourth, fifth, and sixth embodiments of the present invention solve the problems by providing the variable displacement oil pump, in which the spool valve is used as a valve for controlling operation of the cam ring, the control chamber and the valve housing of the spool valve communicate with each other, the spool valve has the valve housing, a spool valve body, a spring, and a sealing bolt, the valve housing has a communication hole provided in the pump housing to supply oil into the control chamber of the pump chamber and the valve housing between the spool valve body of the valve housing and the sealing bolt, and a through-hole for discharging oil of the valve housing is provided in the sealing bolt. Seventh, eighth, and ninth embodiments of the present invention solve the problems by providing the variable displacement oil pump, in which the sealing bolt has a cylindrical restricting protrusion formed to restrict a movement range of the spool valve body or stop a movement of the spool valve body. Tenth, eleventh, and twelfth embodiments of the present invention solve the problems by providing the variable displacement oil pump, in which the communication hole is an orifice. Thirteenth, fourteenth, and fifteenth embodiments of the invention solve the problems by providing the variable displacement oil pump, in which the communication hole is provided in a cover of the pump housing.

Sixteenth, seventeenth, and eighteenth embodiments of the present invention solve the problems by providing the variable displacement oil pump, in which the relief valve is used as a valve for controlling operation of the cam ring, the control chamber and the valve housing of the relief valve communicate with each other, the relief valve has the valve housing, a relief valve body, and a relief spring, the valve housing has the relief valve body, a relief chamber closed by an elastic member, and a relief vent opened to the outside at all time, and the communication hole communicates with the relief vent of the valve housing. Nineteenth and twentieth embodiments of the present invention solve the problems by providing the variable displacement oil pump, in which the solenoid valve is used as a valve for controlling operation of the cam ring, the control chamber and the valve housing of the solenoid valve communicate with each other, the solenoid valve has the valve housing, the solenoid valve body, and a solenoid control unit, and the control chamber communicates with a non-reaching region of the solenoid valve body of the solenoid valve chamber of the valve housing.

According to the present invention, the valve housing has a communication hole provided in the pump housing to supply oil from the control chamber between the control chamber of the pump chamber and at least one of the spool valve, the solenoid valve, and the relief valve. Therefore, it is possible to intentionally transmit the oil pressure of the control chamber for controlling operation of the cam ring inside the pump chamber into the valve housing. As a result, the oil transmitted to a gap between the inner wall of the valve housing and the valve body enters the valve housing of any one of the valves to serve as a lubricant, so that it is possible to further facilitate a sliding movement of the valve body.

Since the oil filled in the control chamber of the pump chamber is transmitted to any one of the valve housings of the spool valve, the solenoid valve, and the relief valve via the communication hole, it is possible to alleviate a pressure spike of the oil inside the control chamber caused by pulsation generated by operating the pump, stabilize behaviors of the members such as the cam ring and the rotor portion, and obtain a stable discharge operation. In this manner, it is possible to alleviate hunting in the variable displacement oil pump.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a front view illustrating a variable displacement oil pump according to the present invention;

FIG. 1B is a front view partially cut away to illustrate a cross section of a spool valve;

FIG. 1C is a cross-sectional view taken along a line Y1-Y1 of FIG. 1A;

FIG. 2A is a cross-sectional view separately illustrating a pump housing and a spool valve according to the present invention when a discharge amount is maximized;

FIG. 2B is a cross-sectional view separately illustrating the pump housing and the spool valve according to the present invention when the discharge amount becomes nearly zero;

FIG. 3 is a schematic diagram illustrating a general configuration according to the present invention;

FIG. 4A is an enlarged cross-sectional view illustrating operation of the spool valve;

FIG. 4B is an enlarged view illustrating a (α)-portion of FIG. 4A;

FIG. 4C is a perspective view illustrating main parts around a communication hole according to the present invention;

FIG. 5A is a perspective view illustrating the variable displacement oil pump according to the present invention;

FIG. 5B is a perspective view illustrating a cover of the pump housing;

FIG. 6A is a perspective view illustrating the variable displacement oil pump according to the present invention as seen from the relief valve and the solenoid valve side;

FIG. 6B is a perspective view illustrating a lower part of the variable displacement oil pump as seen from the relief valve and the solenoid valve side;

FIG. 7A is a partial cross-sectional rear view illustrating the variable displacement oil pump according to the present invention;

FIG. 7B is a cross-sectional view taken along a line X1-X1 of FIG. 7A;

FIG. 7C is a cross-sectional view taken along a line X2-X2 of FIG. 7A;

FIG. 8A is a cross-sectional view separately illustrating the pump housing and the relief valve according to a second embodiment of the present invention when the discharge amount is maximized;

FIG. 8B is a cross-sectional view separately illustrating the pump housing and the relief valve according to the present invention when the discharge amount becomes nearly zero;

FIG. 9 is a schematic diagram illustrating a general configuration according to a second embodiment of the present invention;

FIG. 10A is a cross-sectional view separately illustrating the pump housing and the solenoid valve according to a third embodiment of the present invention when the discharge amount is maximized;

FIG. 10B is a cross-sectional view separately illustrating the pump housing and the solenoid valve according to the present invention when the discharge amount becomes nearly zero;

FIG. 11 is a schematic diagram illustrating a general configuration according to a third embodiment of the present invention;

FIG. 12 is a schematic diagram illustrating a general configuration in which the rotor portion according to the first embodiment of the present invention is an inscribed gear; and

FIG. 13 is a schematic diagram illustrating a general configuration in which the rotor portion according to the second embodiment of the present invention is an inscribed gear.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. A variable displacement oil pump according to the present invention is a vane pump type oil pump integrated into an oil lubrication circuit of a device such as an engine. The variable displacement oil pump according to the present invention includes a rotor portion 2A, a cam ring 21 having a rotor chamber 21 a, a pump housing 1 having a pump chamber 11 provided with a control chamber 12, and a spool valve A that controls operation of the cam ring 21 (see FIGS. 5A, 5B, 1A to 1C, 2A, 2B, and 4A). There are a vane pump and an inscribed gear pump as the variable displacement oil pump according to the present invention depending on the configuration of the rotor portion 2A. In addition, in the case of the vane pump, the rotor portion 2A has a vane rotor 22 and a vane 23. In the case of the inscribed gear pump, the rotor portion 2A has an inner rotor 26 and an outer rotor 27.

The present invention provides a plurality of embodiments. First, a first embodiment will be described. According to the first embodiment, a valve for controlling the operation of the cam ring 21 is the spool valve A. A communication hole 7 for allowing the spool valve A and the control chamber 12 of the pump chamber 11 to communicate with each other is provided. In addition, a solenoid valve 81 for operating the spool valve A, an ECU 82 for supplying an operational signal to the solenoid valve 81, and a relief valve 83 may also be provided (see FIG. 3).

The pump housing 1 has a housing body portion 1A and a cover 1B (see FIGS. 5A and 5B). The housing body portion 1A has a pump chamber 11 and a shaft hole. The pump chamber 11 has an inlet port 11 a and an outlet port 11 b (see FIGS. 2A and 2B). In addition, the control chamber 12 is provided in an area of the pump chamber 11 (see FIGS. 2A and 2B). The pump chamber 11 may house the cam ring 21, the rotor portion 2A, a drive shaft 24, a compressed coil spring 25, or the like. In the following description, the rotor portion 2A is described as a vane pump having the vane rotor 22 and the vane 23. However, if the rotor portion 2A is substituted with an inner rotor 26 and an outer rotor 27, an inscribed gear pump type variable displacement oil pump can be obtained.

The cam ring 21 has a rotor chamber 21 a (see FIGS. 2A and 2B). The rotor chamber 21 a is a circular cavity that houses the vane rotor 22 and the vanes 23. The cam ring 21 has a substantially square or rectangular shape. The cam ring 21 is arranged to straightly reciprocate inside the pump chamber 11. Therefore, arbitrary opposing end sides of the cam ring 21 move along both facing side walls of the pump chamber 11 as a guide. Inside the rotor chamber 21 a of the cam ring 21, the drive shaft hole is positioned, and the drive shaft 24 is placed.

The vane rotor 22 has a plurality of vane trench portions 22 a, 22 a, . . . where the vanes 23, 23 . . . are inserted (see FIGS. 2A and 2B) thereinto. The vane rotor 22 is assembled to the pump chamber 11 of the pump housing 1 by maintaining its rotation center in a stationary state, so that it is fixed to the drive shaft 24 and is rotated by engine power or a motor. As the vane rotor 22 rotates, the vane 23 protrudes out of the vane trench portion 22 a by virtue of a centrifugal force, a guide ring, or the like, and abuts on the inner wall of the rotor chamber 21 a of the cam ring 21.

The cam ring 21 is housed in the pump chamber 11 of the pump housing 1 along with a compressed coil spring 25, and the compressed coil spring 25 constantly presses the cam ring 21 toward one side of the pump chamber 11 (see FIG. 2A). In this state, the cam ring 21, the vane rotor 22, and the vane 23 are maintained in a state where the discharge amount is maximized, and a distance between a diameter center of the vane rotor 22 and a diameter center of the rotor chamber 21 a becomes farthest. That is, the eccentricity is maximized.

When the cam ring 21 moves toward the other side of the pump chamber 11 against the elastic force of the compressed coil spring 25 as the oil pressure supplied from the spool valve into the control chamber 12 increases, the distance between the diameter center of the rotor chamber 21 a and the diameter center of the vane rotor 22 is reduced, and the oil discharge amount decreases. In addition, when the diameter center of the rotor chamber 21 a is concentric to the diameter center of the vane rotor 22, the oil discharge operation approaches zero (see FIG. 2B).

The control chamber 12 of the pump chamber 11 is specifically a cavity chamber formed between the pump chamber 11 and the cam ring 21 housed in the pump chamber 11, and its position is symmetrically opposite to the compressed coil spring 25 housed in the pump chamber 11 with respect to the cam ring 21 (see FIGS. 2A and 2B). As described below, the control chamber 12 has a communication hole 7 through which oil flows to the spool valve A, and the communication hole 7 is used to transmit the oil of the control chamber 12 to the spool valve A side.

The control chamber 12 is a cavity, and formation of this cavity will now be described. First, a protrusion is formed at one end in a movement direction of the cam ring 21, and a cavity is formed while the cam ring 21 abuts on a side wall of one side of the pump chamber 11. In addition, a recess may be provided on a wall surface of one end side of the pump chamber 11, so that a cavity formed by this recess is used as the control chamber 12. The control chamber 12 is a part of the pump chamber 11 and is a cavity chamber smaller than the entire pump chamber 11. The oil supply to the control chamber 12 is performed by the spool valve A.

The spool valve A has a valve housing 3, a spool valve body 4, a spring 5, a sealing bolt 6, and a communication hole 7 (see FIGS. 1C and 4A to 4C). A structure of the spool valve A will be described, and then, the communication hole 7 will be described in details. The valve housing 3 is formed integrally with the pump housing 1. Preferably, the valve housing 3 is formed integrally with the cover 1B of the pump housing 1 (see FIGS. 5A and 5B). In addition, the valve housing 3 may also be formed in the housing body portion 1A side, and this is appropriately determined depending on the configuration of the pump housing 1.

A spool chamber 31 is provided inside the valve housing 3, and the spool valve body 4, the spring 5, and the sealing bolt 6 are housed in the spool chamber 31 (see FIGS. 1B, 1C, 2A, 2B, 4A to 4C, and the like). In addition, the spool chamber 31 has a first inflow/outflow portion 31 a, a second inflow/outflow portion 31 b, and a controlled outflow portion 31 c.

The first inflow/outflow portion 31 a is a part through which oil flows in or out via the solenoid valve 81, and the second inflow/outflow portion 31 b is a part through which the oil branched from the flow path of the oil discharged from the oil pump flows in or out. The controlled outflow portion 31 c is a part that supplies oil to the control chamber 12 of the pump chamber 11, so that the cam ring 21 of the pump chamber 11 is moved by supplying the oil to the control chamber 12 in order to adjust the discharge amount (see FIGS. 4A to 4C).

The spool valve body 4 has a spool small-diameter portion 41, a spool large-diameter portion 42, and a neck portion 43, and the neck portion 43 is placed between the spool small-diameter portion 41 and the spool large-diameter portion 42. The spool large-diameter portion 42 has a diameter larger than that of the spool small-diameter portion 41, and the neck portion 43 has a diameter smaller than that of the spool small-diameter portion 41 (see FIG. 4A).

The spool valve body 4 slides in the spool chamber 31, and the spool chamber 31 has a small cavity portion 31 d where only the spool small-diameter portion 41 is slidable. In addition, the first inflow/outflow portion 31 a is provided in the small cavity portion 31 d. Furthermore, in the spool chamber 31, the second inflow/outflow portion 31 b is formed in a step portion having a height different from that of the small cavity portion 31 d (see FIG. 4A).

The sealing bolt 6 has a shank portion 61, a bolt head 62, a restricting protrusion 63, a hollow portion 64, and a through-hole 65 (see FIG. 4A). The sealing bolt 6 is fixed to the valve housing 3. Specifically, in the spool chamber 31 of the valve housing 3, one end side of the movement direction of the spool valve body 4 is opened, and the sealing bolt 6 is installed in this opening.

For joining the sealing bolt 6 and the opening of the spool chamber 31, an outer thread 61 a formed on an outer circumference of the shank portion 61 of the sealing bolt 6 is screwed to an inner thread 31 e formed on an inner circumference of the spool chamber 31 (see FIG. 4A). The bolt head 62 of the sealing bolt 6 is used to install the sealing bolt 6 in the valve housing 3, so that the bolt head 62 is exposed to the outside of the valve housing 3. The restricting protrusion 63 is a part inserted into the spool chamber 31.

The spring 5 is placed between the sealing bolt 6 and the spool valve body 4 inside the spool chamber 31 of the valve housing 3, and the spool valve body 4 is pressed toward a side where the first inflow/outflow portion 31 a of the spool chamber 31 is positioned by virtue of an elastic force of the spring 5, so that the spool small-diameter portion 41 is inserted into the small cavity portion 31 d at all times. The through-hole 65 is a hole provided at a radial center along an axial direction of the sealing bolt 6. The through-hole 65 is used to discharge the oil supplied from the communication hole 7 to the outside of the spool valve A and return the oil to a device such as an oil pan.

In the spool chamber 31, the spool valve body 4 is moved toward the sealing bolt 6 side against the elastic force of the spring 5 by virtue of a force generated by the oil inflow from the first and second inflow/outflow portions 31 a and 31 b and the oil pressure. This movement makes the controlled outflow portion 31 c opened or closed, and this open/close operation allows the oil to be supplied to the control chamber 12 of the pump chamber 11 or stops the supply of oil in order to control the operation of the cam ring 21.

The communication hole 7 is provided between the spool chamber 31 of the valve housing 3 and the control chamber 12 of the pump housing 1 (see FIGS. 1C, 4A to 4C, and the like). In addition, the communication hole 7 is positioned between the spool valve body 4 and the sealing bolt 6 in the spool chamber 31. That is, the communication hole 7 is set such that the oil does not join via the spool valve body 4 between the first and second inflow/outflow portions 31 a and 31 b inside the spool chamber 31.

The communication hole 7 is an oil passage for allowing the spool chamber 31 of the valve housing 3 and the control chamber 12 of the pump housing 1 to communicate with each other and supplying the oil of the control chamber 12 to the spool chamber 31. The communication hole 7 is configured so as not to be shut down (not to be closed) by the movement of the spool valve body 4 inside the spool chamber 31.

Specifically, while the spool valve body 4 is moved inside the spool chamber 31 by the force generated by the oil pressure flowing from the first and second inflow/outflow portions 31 a and 31 b, its movement range is restricted by the restricting protrusion 63 of the sealing bolt 6. That is, the spool valve body 4 abuts on the restricting protrusion 63 and serves as a stopper for forcible stopping.

In the spool chamber 31, at least a part of the communication hole 7 overlaps with a protruding range of the restricting protrusion 63, so that the spool valve body 4 is not allowed to close the communication hole 7, and the communication hole 7 can be maintained in an open state in any situation at all times (see FIGS. 2A, 2B, 4A, 4B, and the like). Here, “at least a part of the communication hole 7 overlaps with the restricting protrusion 63” includes both a case where the entire opening of the spool chamber 31 side of the communication hole 7 is within the protruding range of the restricting protrusion 63 and a case where only a part of the opening of the communication hole 7 is within the protruding range of the restricting protrusion 63.

For such a configuration, a cavity where the oil can circulate is provided between the restricting protrusion 63 and the inner circumference side of the valve housing 3, that is, the inner wall of the spool chamber 31. The communication hole 7 may be an orifice. Here, the orifice is a flow path having a particularly narrow diameter (a diameter of approximately 0.5 to 2.0 mm). If the communication hole 7 is an orifice, a part of the flow path of the communication hole 7 may be narrowed to a smaller diameter, or the entire flow path may have a small diameter.

Since the communication hole 7 is provided between the spool valve A and the control chamber 12 of the pump chamber 11, the oil inside the control chamber 12 for operating or controlling the cam ring 21 in the pump chamber 11 can be intentionally supplied to the spool chamber 31 of the valve housing 3. As a result, in the valve housing 3 of the spool valve A, the supplied oil enters a gap between the inner wall of the spool chamber 31 of the valve housing 3 and the spool large-diameter portion 42 of the spool valve body 4, and this serves as a lubricant. Therefore, it is possible to further facilitate the sliding movement of the spool valve body 4 inside the spool chamber 31 (see FIGS. 4A and 4B).

Since the oil filled in the control chamber 12 of the pump chamber 11 is supplied into the valve housing 3 of the spool valve A via the communication hole 7, a pressure spike of the oil in the control chamber 12 caused by pulsation of the oil by operating the vane pump is alleviated. As a result, due to the stable oil operation, it is possible to stabilize behaviors of the members such as the cam ring 21, the vane rotor 22, and the vane 23 and obtain a stable discharge operation. In this manner, it is possible to alleviate hunting in the variable displacement oil pump.

Since the through-hole 65 for discharging the oil of the valve housing 3 is provided in the sealing bolt 6, the oil supplied from the control chamber 12 of the pump chamber 11 into the valve housing 3 is discharged from the valve housing 3 to the oil fan or the like via the through-hole 65. As a result, the oil supplied into the valve housing 3 serves as a lubricant, so that it is possible to improve slidability of the spool valve body 4 and prevent difficulty in the sliding movement of the spool valve body 4 inside the spool chamber 31, particularly, in a receding movement. When the communication hole 7 is an orifice, it is possible to reduce the amount of oil discharged in the control chamber 12 of the pump chamber 11 to a very small amount, and optimize the operation control of the cam ring using the control chamber 12.

Next, a second embodiment of the present invention will be described. According to the second embodiment, a valve for controlling the operation of the cam ring 21 is the relief valve 83. According to the second embodiment, the control chamber 12 of the pump housing 1 and the relief valve 83 communicate with each other via the communication hole 7, so that the oil discharged from the control chamber 12 is discharged to the oil pan or the like via the valve housing 831 of the relief valve 83 (see FIGS. 7B, 8A, 8B and 9). The relief valve 83 is provided on the back side opposite to the side of the pump housing 1 where the spool valve A is installed (see FIGS. 6A and 6B).

The relief valve 83 includes a valve housing 831, a relief valve body 832, a relief spring 833, and a relief sealing bolt 834. The valve housing 831 internally has a relief chamber 831 a and a relief vent 831 c (see FIGS. 7A, 7B, 8A and 8B). In addition, the relief sealing bolt 834 has a through-hole 834 a. The relief sealing bolt 834 is formed in a bolt cap shape and has an outer thread. The discharge port of the relief vent 831 c has an inner thread, where the outer thread of the relief sealing bolt 834 is fastened by screwing for installation.

An oil inlet 831 b is formed in the relief chamber 831 a of the valve housing 831, so that the relief oil flows from the oil inlet 831 b into the relief chamber 831 a when the oil pump is relieved (see FIGS. 8A and 8B). In addition, the relief vent 831 c is provided continuously to the relief chamber 831 a.

The relief vent 831 c is provided with the relief valve body 832 and the relief spring 833, and the relief sealing bolt 834 is installed in the discharge port of the relief vent 831 c. The relief spring 833 is positioned between the relief sealing bolt 834 and the relief valve body 832, so that the relief valve body 832 is elastically biased by virtue of the elastic force of the relief spring 833 so as to close the vicinity of the outlet port of the relief chamber 831 a at all times.

When the oil pump is relieved, the pressure of the relief oil flowing from the oil inlet 831 b increases over the elastic force of the relief spring 833, so that the relief valve body 832 is pushed down from the outlet port of the relief chamber 831 a for relief, and the discharged oil is returned from the relief vent 831 c to the inlet side of the oil pump via the through-hole 834 a of the relief sealing bolt 834.

The communication hole 7 of the control chamber 12 communicates with the relief vent 831 c side of the valve housing 831 (see FIGS. 8A, 8B and 9). The communication holes 7 for allowing the valve housing 831 of the relief valve 83 and the control chamber 12 to communicate with each other communicate with each other via a communication passage 7 a having a channel shape. Since the communication hole 7 of the control chamber 12 communicates with the relief vent 831 c via the communication passage 7 a, the operation does not interfere with the relief operation of the relief chamber 831 a side. In addition, since the relief vent 831 c has the communication passage 7 a of the communication hole 7, the oil discharged from the communication hole 7 is directly and simply discharged via the through-hole 834 a of the relief sealing bolt 834, the discharge oil passage communicating with the through-hole 834 a, or the like (see FIG. 8B). Although the through-hole 834 a is provided in the relief sealing bolt 834 in this embodiment, the same effect can be achieved by providing the through-hole in the pump housing 1 to return the oil to the inlet side of the oil pump.

Next, a third embodiment of the present invention will be described. According to the third embodiment, a valve for controlling the operation of the cam ring 21 is the solenoid valve 81. According to the third embodiment, the control chamber 12 of the pump housing 1 and the solenoid valve 81 communicate with each other via the communication hole 7, so that the oil discharged from the control chamber 12 is discharged to the oil pan or the like via the valve housing 811 of the solenoid valve 81 (see FIGS. 7C, 10A, 10B, and 11).

As described above, the solenoid valve 81 is used to operate the spool valve A using the ECU 82 (see FIG. 11). Along with the relief valve 83, the solenoid valve 81 is provided on the back side of the pump housing 1 opposite to the side where the spool valve A is installed (see FIGS. 6A and 6B). The solenoid valve 81 includes a valve housing 811, a solenoid valve body 812, and a solenoid control unit 813.

A solenoid valve chamber 811 a is provided in the valve housing 811, and the solenoid valve body 812 is installed in the solenoid valve chamber 811 a. The solenoid valve body 812 slides in the axial direction inside the solenoid valve chamber 811 a by virtue of an electromagnetic action of the solenoid control unit 813. The solenoid valve chamber 811 a has an operational channel for operating the spool valve A, so that the operational channel is opened or closed by the solenoid valve body 812.

Similar to the second embodiment, for communication between the valve housing 811 of the solenoid valve 81 and the communication hole 7 of the control chamber 12, the communication passage 7 a and the solenoid valve chamber 811 a communicate with each other (see FIG. 11). Here, the communication hole 7 is formed in a non-reaching region 811 b, that is, a portion of the solenoid valve chamber 811 a where the solenoid valve body 812 does not reach (see FIGS. 7C, 10A and 10B).

In other words, the non-reaching region 811 b is a cavity portion formed between a tip of the solenoid valve body 812 and the solenoid valve chamber 811 a when the solenoid valve body 812 moves and stops at the maximum position in the axial direction by virtue of the electromagnetic action of the solenoid control unit 813. In addition, a through-hole 814 for discharging the oil to the outside is formed in the non-reaching region 811 b of the solenoid valve body 812 of the solenoid valve chamber 811 a, so that the oil discharged from the communication hole 7 of the control chamber 12 is discharged from the through-hole 814 at all times (see FIG. 10B).

Communication with the communication hole 7 of the control chamber 12 is communication with at least any one of the spool valve A, the relief valve 83, and the solenoid valve 81 in principle. Therefore, the communication hole 7 from the control chamber 12 may be configured to communicate with one of the valve housings. According to the present invention, without limiting to the configuration described above, the communication with the communication hole 7 of the control chamber 12 may be communication with two, or two or more valve housings of the spool valve A, the relief valve 83, and the solenoid valve 81.

Next, a variable displacement oil pump according to the present invention obtained by applying an inscribed gear type rotor portion 2A to the first embodiment described above will be described with reference to FIG. 12. The rotor portion 2A includes an inner rotor 26 and an outer rotor 27 (see FIG. 12). A shaft hole of the drive shaft 24 is formed in the pump chamber 11, and an inlet port 11 a and an outlet port 11 b are formed around the shaft hole.

A first seal land 11 c is provided between a terminated end of the inlet port 11 a and a start end of the outlet port 11 b, and a second seal land 11 d is provided between a terminated end of the outlet port 11 b and a start end of the inlet port 11 a. The control chamber 12 continuous to the pump chamber 11 is formed in the pump housing 1 and is placed in the operational protrusion 211 of the cam ring 21 as described below. The rotor portion 2A including the inner rotor 26 and the outer rotor 27 and the cam ring 21 are housed in the pump chamber 11 (see FIG. 12).

The inner rotor 26 is a gear having a trochoid shape or a substantial trochoid shape and has a plurality of outer teeth. In addition, a boss hole for the drive shaft 24 is formed at the center position in the radial direction, and the drive shaft 24 is penetratingly fixed to the boss hole. The outer rotor 27 is formed in an annular shape, and a plurality of inner teeth are formed in the inner circumferential side. The number of the outer teeth of the inner rotor 26 is less than the number of the inner teeth of the outer rotor 27 by one. The outer teeth of the inner rotor 26 and the inner teeth of the outer rotor 27 form a plurality of cells (inter-tooth spaces) S.

A distance between a rotation center Pa of the inner rotor 26 and a rotation center Pb of the outer rotor 27 is set as an eccentricity, and a locus circle is formed by setting the rotation center Pa of the inner rotor 26 as a center and setting the eccentricity as a radius. As the cam ring 21 is operated, the rotation center Pb of the outer rotor 27 moves along a substantially fan-shaped arc as a part of a locus circle from an initial position state to a final position state. The cam ring 21 is formed substantially in an annular shape and has an operational protrusion 211 formed to protrude outward in the radial direction from a predetermined portion on the outer circumferential surface. In addition, a holding inner-circumferential portion 21 c as a perfect circular through-hole is formed inside the cam ring 21. The cam ring 21 is operated to swing inside the pump chamber 11 using the operational protrusion 211.

The operational protrusion 211 is disposed in the control chamber 12 and is swingable inside the control chamber 12. The holding inner-circumferential portion 21 c is formed as a circular inner wall surface of the rotor chamber 21 a, and has an inner diameter substantially matching the outer diameter of the outer rotor 27. Specifically, the holding inner-circumferential portion 21 c has the inner diameter slightly larger than the outer diameter of the outer rotor 27. In addition, the outer rotor 27 is inserted with a suitable clearance between the holding inner-circumferential portion 21 c and the outer rotor 27 such that the outer rotor 27 can smoothly rotate.

The holding inner-circumferential portion 21 c of the cam ring 21 has a diameter center matching the position of the rotation center Pb of the outer rotor 27 when the outer rotor 27 is inserted into the holding inner-circumferential portion 21 c. The cam ring 21 is housed in the pump chamber 11 of the pump housing 1, so as to be swingable inside the pump chamber 11. The swing operation of the cam ring 21 is performed by the spool valve A and the solenoid valve 81. The operational protrusion 211 has a first pressure-receiving surface 211 a formed on one side of the swinging direction and a second pressure-receiving surface 211 b formed on the other side.

The operational protrusion 211 is configured to bisect the control chamber 12 while it is placed inside the control chamber 12. Inside the control chamber 12, a hydraulic chamber facing the first pressure-receiving surface 211 a is set as a first chamber 12 a, and a hydraulic chamber facing the second pressure-receiving surface 211 b is set as a second chamber 12 b.

The control chamber 12 has a compressed coil spring 25. The compressed coil spring 25 elastically presses the second pressure-receiving surface 211 b of the cam ring 21, so that the cam ring 21 and the outer rotor 27 are biased to the initial positions at all times. In addition, a first oil passage 13 a communicating with the first chamber 12 a and a second oil passage 13 b communicating with the second chamber 12 b are provided between the control chambers 12 and the spool valve A.

The spool valve A supplies the oil to the first chamber 12 a of the control chamber 12 via the first oil passage 13 a or supplies the oil to the second chamber 12 b via the second oil passage 13 b, so that the cam ring 21 is rotated clockwise or counterclockwise along with the operational protrusion 211. The rotation of the cam ring 21 displaces the position of the outer rotor 27 and changes the discharge amount.

The spool valve A has a valve housing 3, a spool valve body 4, and a spool elasticity member 45. The valve housing 3 internally has a spool chamber 31 (see FIGS. 12 and 13). A pair of controlled outflow portions 31 c are respectively provided in one end side of the axial direction of the spool chamber 31 (in the movement direction of the spool valve body 4) and in a substantially middle portion (see FIGS. 12 and 13). One of the two controlled outflow portions 31 c communicates with the first chamber 12 a of the control chamber 12, and the other controlled outflow portion 31 c communicates with the second chamber 12 b of the control chamber 12.

The spool valve body 4 is slidably disposed inside the spool chamber 31. In addition, the spool valve body 4 slides in the spool chamber 31 by receiving the hydraulic pressure from a valve operation oil passage 31 f provided in the spool chamber 31. The spool elasticity member 45 is housed in the spool chamber 31, so that the spool valve body 4 is elastically biased toward the valve operation oil passage 31 f in the movement direction of the spool chamber 31.

The sealing bolt 6 is provided in the end of the spool chamber 31 to make the spool chamber 31 a closed space. The movement of the spool valve body 4 in the spool chamber 31 is performed by the solenoid valve 81. The solenoid valve 81 has a directional control valve 85, and the directional control valve 85 is operated by electromagnetic operation. The directional control valve 85 controls the movement of the spool valve body 4 of the spool valve A by controlling the flow direction of the oil inside the solenoid valve 81.

The spool valve body 4 slides in the spool chamber 31 by the operation of the solenoid valve 81 and appropriately switches a pair of the controlled outflow portions 31 c so as to open one of them and close the other one. Accordingly, the oil is transmitted to any one of the first and second chambers 12 a and 12 b of the control chamber 12, and the oil is discharged from the other one. In addition, the cam ring 21 swings by operating the operational protrusion 211 of the cam ring 21 inside the control chamber 12. As a result, the position of the outer rotor 27 in the pump chamber 11 changes, and the discharge amount changes.

Similar to the first to third embodiments, the communication hole 7 used to supply the oil from the control chamber 12 to the valve housing 3 is formed in the control chamber 12. Specifically, the communication hole 7 is formed in the second chamber 12 b side of the control chamber 12. In addition, the communication hole 7 may also be provided in the first chamber 12 a side. Furthermore, the communication hole 7 may be provided in both the second chamber 12 b and the first chamber 12 a of the control chamber 12.

When the spool valve A is used as a valve for controlling the operation of the cam ring 21, the communication hole 7 is provided in the housing side of the spool elasticity member 45 of the spool chamber 31 of the spool valve A, and the communication holes 7 of the spool valve A and the control chamber 12 communicate with each other via the communication passage 7 a. In addition, the through-hole 65 is provided in the sealing bolt 6, and the oil supplied from the control chamber 12 to the spool valve A is discharged from the through-hole 65 of the sealing bolt 6.

Next, a variable displacement oil pump according to the present invention obtained by applying the inscribed gear type rotor portion 2A to the second embodiment described above will be described with reference to FIG. 13. That is, when the relief valve 83 is used to control the operation of the cam ring 21, the cam ring 21 communicates with the housing side of the spool elasticity member 45 of the spool chamber 31 of the relief valve 83 (see FIG. 13). Here, the employed relief valve 83 has the same structure and performs the same operation as those of the second embodiment of the invention (see FIGS. 8A, 8B and 9). Therefore, the communication hole 7 of the control chamber 12 communicates with the relief vent 831 c side of the valve housing 831 of the relief valve 83.

The communication holes 7 used to communicate the valve housing 831 of the relief valve 83 and the control chamber 12 communicate with each other via the communication passage 7 a. In addition, the oil discharged from the communication hole 7 of the relief valve 83 directly flows through the relief vent 831 c and is simply discharged via the through-hole 834 a of the relief sealing bolt 834, a discharge oil passage communicating with the through-hole 834 a, or the like.

Since the communication hole 7 of the control chamber 12 communicates with the relief vent 831 c via the communication passage 7 a, there is no interference with the relief operation of the relief chamber 831 a side. Note that, in FIGS. 8A, 8B and 9, the reference numeral “9” refers to an oil circuit circulating between the variable displacement oil pump according to the present invention and the engine. The solenoid valve 81 communicates with a branching channel 91 of the oil circuit 9, so that the oil is supplied from the branching channel 91 of the oil circuit 9 to the spool valve A via the solenoid valve 81.

Note that, when the relief valve 83 is used as a valve for controlling the operation of the cam ring 21, a part of the operation of the cam ring 21 is controlled by the relief valve 83, and the main operation of the cam ring 21 is controlled by the spool valve A, the solenoid valve 81, or the like.

In this case, since the communication hole 7 is provided in the relief valve 83, and the oil filled in the control chamber 12 is transmitted into the valve housing 831 via the relief valve 83, behaviors of the members such as the cam ring 21 and the rotor portion 2A are stabilized to alleviate hunting of the variable displacement oil pump.

When the solenoid valve 81 is used as a valve for controlling the operation of the cam ring 21, the main operation of the cam ring 21 is controlled along with the spool valve A, and the communication hole 7 is provided in the solenoid valve 81. Therefore, behaviors of the members such as the cam ring 21 and the rotor portion 2A are stabilized using the solenoid valve 81 to alleviate hunting of the variable displacement oil pump.

According to the second embodiment, the rotor portion has the vane rotor and a plurality of vanes. Therefore, it is possible to alleviate hunting of the variable displacement pump particularly in the vane pump type. According to the third embodiment, the rotor portion has the inner rotor having outer teeth and the outer rotor that has inner teeth that form cells along with the outer teeth and rotate with a predetermined eccentricity with respect to a rotation center of the inner rotor. A protrusion is formed on the outer circumference of the cam ring, and is placed in the control chamber. Therefore, it is possible to alleviate hunting of the variable displacement pump as an inscribed type gear pump such as a trochoid type.

According to the fourth, fifth, and sixth embodiments, in the spool valve, the oil transmitted from the control chamber of the pump chamber into the valve housing is discharged from the outside of the pump housing to the oil pan or the like via the through-hole. In this manner, since the communication hole is provided between the spool valve and the control chamber of the pump chamber, and the oil of the control chamber is intentionally supplied to the spool chamber of the valve housing, the supplied oil enters a gap between the inner wall of the spool chamber and the spool valve body in the valve housing and serves as a lubricant. Therefore, it is possible to further facilitate a sliding movement of the spool valve body inside the spool chamber. In addition, since the through-hole for discharging the oil of the valve housing is provided as described above, the oil transmitted into the valve housing improves the sliding movement of the spool valve body and prevents difficulty, particularly, in the receding movement of the spool valve body.

According to the seventh, eighth, and ninth embodiments, the sealing bolt has the cylindrical restricting protrusion formed to restrict a movement range of the spool or stop the movement of the spool. Therefore, even when the spool valve body moves toward the sealing bolt side over a movement range of the spool valve body due to an abnormal pressure, it is possible to stop the movement of the spool valve body and maintain safety because the spool valve body abuts on the restricting protrusion.

According to the tenth, eleventh, and twelfth embodiments, an orifice (having a small diameter of approximately 0.5 to 2.0 mm) is employed as the communication hole. Therefore, it is possible to set a discharge amount of the oil of the control chamber of the pump chamber to a very small amount, and prevent an abrupt movement in the operation of the cam ring inside the control chamber. According to the thirteenth, fourteenth, and fifteenth embodiments, the communication hole is provided in the cover of the pump housing. Therefore, it is possible to facilitate a disassembling work in maintenance and improve efficiency of the maintenance work. Furthermore, since the length of the communication hole is minimized, it is possible to transmit the oil into the valve housing with excellent responsiveness.

Note that a cavity where oil can flow is provided between the restricting protrusion of the sealing bolt and the inner circumference side of the valve housing, and the communication hole is positioned within a protruding range of the restricting protrusion. Therefore, the communication hole is not blocked by the restricting protrusion or the spool valve body, and the oil flowing from the control chamber into the pump chamber can be sufficiently secured by the cavity.

If a hollow portion for housing or holding an axial tip of the spring is provided in the sealing bolt, it is possible to further stabilize a behavior of the spring arranged between the sealing bolt and the spool valve body. In addition, it is possible to shorten the axial length of the valve housing. Similar to the first, second, and third embodiments, according to the sixteenth, seventeenth, and eighteenth embodiments, it is possible to alleviate a pressure spike of the oil in the control chamber caused by pulsation generated by operating the pump, stabilize behaviors or the members such as the cam ring and the rotor portion, and obtain a stable discharge operation. In this manner, it is possible to alleviate hunting of the variable displacement oil pump. Similarly, according to the nineteenth and twentieth embodiments, it is possible to obtain the same effects as those of the sixteenth, seventeenth, and eighteenth embodiments. 

What is claimed is:
 1. A variable displacement oil pump comprising: a rotor portion; a cam ring having a rotor chamber for housing the rotor portion; a pump housing provided with a pump chamber having a control chamber where the cam ring is movably arranged to move the cam ring using an oil pressure; a spool valve; a solenoid valve; and a relief valve, wherein at least one of the spool valve, the solenoid valve, and the relief valve has a valve housing provided with a communication hole for supplying oil from the control chamber to a portion between the control chamber of the pump chamber and at least one of the valve housings, and a through-hole for discharging oil is formed in the valve housing provided with the communication hole.
 2. The variable displacement oil pump according to claim 1, wherein the rotor portion includes a vane rotor and a plurality of vanes.
 3. The variable displacement oil pump according to claim 1, wherein the rotor portion has an inner rotor having outer teeth and an outer rotor that has inner teeth that form cells along with the outer teeth and rotates with a predetermined eccentricity with respect to a rotation center of the inner rotor, a protrusion is formed in an outer circumference of the cam ring, and the protrusion is placed in the control chamber.
 4. The variable displacement oil pump according to claim 1, wherein the spool valve is used as a valve for controlling operation of the cam ring, the control chamber and the valve housing of the spool valve communicate with each other, the spool valve has the valve housing, a spool valve body, a spring, and a sealing bolt, the valve housing has a communication hole provided in the pump housing to supply oil into the control chamber of the pump chamber and the valve housing between the spool valve body of the valve housing and the sealing bolt, and a through-hole for discharging oil of the valve housing is provided in the sealing bolt.
 5. The variable displacement oil pump according to claim 2, wherein the spool valve is used as a valve for controlling operation of the cam ring, the control chamber and the valve housing of the spool valve communicate with each other, the spool valve has the valve housing, a spool valve body, a spring, and a sealing bolt, the valve housing has a communication hole provided in the pump housing to supply oil into the control chamber of the pump chamber and the valve housing between the spool valve body of the valve housing and the sealing bolt, and a through-hole for discharging oil of the valve housing is provided in the sealing bolt.
 6. The variable displacement oil pump according to claim 3, wherein the spool valve is used as a valve for controlling operation of the cam ring, the control chamber and the valve housing of the spool valve communicate with each other, the spool valve has the valve housing, a spool valve body, a spring, and a sealing bolt, the valve housing has a communication hole provided in the pump housing to supply oil into the control chamber of the pump chamber and the valve housing between the spool valve body of the valve housing and the sealing bolt, and a through-hole for discharging oil of the valve housing is provided in the sealing bolt.
 7. The variable displacement oil pump according to claim 4, wherein the sealing bolt has a cylindrical restricting protrusion formed to restrict a movement range of the spool valve body or stop a movement of the spool valve body.
 8. The variable displacement oil pump according to claim 5, wherein the sealing bolt has a cylindrical restricting protrusion formed to restrict a movement range of the spool valve body or stop a movement of the spool valve body.
 9. The variable displacement oil pump according to claim 6, wherein the sealing bolt has a cylindrical restricting protrusion formed to restrict a movement range of the spool valve body or stop a movement of the spool valve body.
 10. The variable displacement oil pump according to claim 1, wherein the communication hole is an orifice.
 11. The variable displacement oil pump according to claim 2, wherein the communication hole is an orifice.
 12. The variable displacement oil pump according to claim 3, wherein the communication hole is an orifice.
 13. The variable displacement oil pump according to claim 1, wherein the communication hole is provided in a cover of the pump housing.
 14. The variable displacement oil pump according to claim 2, wherein the communication hole is provided in a cover of the pump housing.
 15. The variable displacement oil pump according to claim 3, wherein the communication hole is provided in a cover of the pump housing.
 16. The variable displacement oil pump according to claim 1, wherein the relief valve is used as a valve for controlling operation of the cam ring, the control chamber and the valve housing of the relief valve communicate with each other, the relief valve has the valve housing, a relief valve body, and a relief spring, the valve housing has the relief valve body, a relief chamber closed by an elastic member, and a relief vent opened to the outside at all time, and the communication hole communicates with the relief vent of the valve housing.
 17. The variable displacement oil pump according to claim 2, wherein the relief valve is used as a valve for controlling operation of the cam ring, the control chamber and the valve housing of the relief valve communicate with each other, the relief valve has the valve housing, a relief valve body, and a relief spring, the valve housing has the relief valve body, a relief chamber closed by an elastic member, and a relief vent opened to the outside at all time, and the communication hole communicates with the relief vent of the valve housing.
 18. The variable displacement oil pump according to claim 3, wherein the relief valve is used as a valve for controlling operation of the cam ring, the control chamber and the valve housing of the relief valve communicate with each other, the relief valve has the valve housing, a relief valve body, and a relief spring, the valve housing has the relief valve body, a relief chamber closed by an elastic member, and a relief vent opened to the outside at all time, and the communication hole communicates with the relief vent of the valve housing.
 19. The variable displacement oil pump according to claim 1, wherein the solenoid valve is used as a valve for controlling operation of the cam ring, the control chamber and the valve housing of the solenoid valve communicate with each other, the solenoid valve has the valve housing, the solenoid valve body, and a solenoid control unit, and the control chamber communicates with a non-reaching region of the solenoid valve body of the solenoid valve chamber of the valve housing.
 20. The variable displacement oil pump according to claim 2, wherein the solenoid valve is used as a valve for controlling operation of the cam ring, the control chamber and the valve housing of the solenoid valve communicate with each other, the solenoid valve has the valve housing, the solenoid valve body, and a solenoid control unit, and the control chamber communicates with a non-reaching region of the solenoid valve body of the solenoid valve chamber of the valve housing. 